Re: [Cerowrt-devel] performance numbers from WRT1200AC (Re: Latest build test - new sqm-scripts seem to work; "cake overhead 40" didn't)

[Dave Taht <dave.taht@gmail.com>]

On Fri, Jun 26, 2015 at 9:35 AM, Jonathan Morton <chromatix99@gmail.com> wrote:
> These would be hardware tail drops - there might not be a physical counter
> recording them. But you could instrument three driver to see whether the
> receive buffer is full when serviced.

from drivers/net/ethernet/marvel/mvneta.c:

/* Max number of Rx descriptors */
#define MVNETA_MAX_RXD 128

this is probably too small, especially given the 64 it is willing to
wait for. At the same time, it is too large, as there are 8 hardware
queues in play here. So you get a huge burst from one flow, it gros it
all together.... aggghh...

/* Max number of Tx descriptors */
#define MVNETA_MAX_TXD 532

this realllllly needs BQL. Same problem(s). Only worse.


>
> - Jonathan Morton
>
>
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-- 
Dave Täht
worldwide bufferbloat report:
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